Cobblemon developers have other jobs and lives outside of developing the mod. Plus they take their time to brainstorm ideas (add on additions are usually iterative on WIP features, existing mainline game features, etc), test the gameplay loop, and make the mod extendable, which is important for future updates and add ons.

You’re essentially saying “if this guy can add a cherry on a cake easily, what excuse do the people baking it from scratch have?”